This invention relates generally to a flexing beam assembly having a neutral plane of zero stress therethrough, and more particularly to an improved construction for weldably connecting a load carrying attachment bracket to an elongated bendable beam such as a lift arm assembly for a loader vehicle.
Many material handling loading vehicles include a pair of lifting beams or arms which are pivotally connected at their proximal ends to the frame of the vehicle and at their distal ends to a load carrying implement. Usually, a pair of hydraulic jacks are connected to the frame and to the lift arms intermediate the opposite ends thereof for selectively raising and lowering the implement to accomplish the desired working tasks. With such construction relatively complex connecting joints have evolved to pivotally couple the lifting jacks to the lift arms. Initially, for example, it was a matter of simply welding an inverted yoke member to the bottom of each of the lift arms and transpiercing a pivot pin through the yoke member to complete the coupling to the top of the lift jacks. However, as the size and lifting capacity of the loading vehicles has increased, concentrated stresses have continued to increase around the yoke members. Subsequent cracking and failure of the yoke members or the weld joints that secure them to the lift arms has led to the development of more massive attachment bracket constructions. But these have required so much weld around the peripheral edges of the brackets that the same failure problems have been experienced. Not only have numerous attempts been made to extend the length of the welds, but multiple layers have been utilized. Nevertheless, despite careful blending of the welds, cracking continues to develop at the areas of maximum stress concentration.